Aston Martin Crash Structure - Coursework Example

Aston Martin Crash Structure Introduction One of the most vital, or important, elements of any car model is the crash beam structure. The crash beam interconnects different components of a given car; the crash houses the drive train or engine and protects and carries both the passengers and engine. The crash beam structure is required to be rigid in order to support stress and weight and to effectively secure or tie together the other car components (Materials Today, 2008). In addition, the crash beam must soften and resist the impact of crash at any accident event in order to safely protect the car occupants. Furthermore, it is required to be as light as possible in order to optimize the fuel economy and increase the car performance. An Aston Martin crash beam has had various designs over the years, and each of the designs has its drawbacks and benefits (Zhao, 2013). The adventure with the composite materials started in 1953 and has advanced. The composites have demonstrated reliability, fatigue resistance, lightweight, and easy moulding to any shape; the composites are attractive alternatives to metals. Despite their merits, there are minimal transfers from metals to the composites in the automotive industry (Startsev, Ponomareva and Anikhovskaya, 2013). For proper utilisation of the composites in crash beam manufacture, issue of: design, structural simulation, light-weighting, modelling, the crashworthiness, joining, manufacturing, repair, recycling and the new material concepts. Priorities in the manufacture of the crash beam include: Development of the automated crash beam manufacturing processes via composite materials. The cost reduction of composite material. Figure 1. The summary of the crash beam manufacture themes The identification and addressing of the material research, for composites, needs of the crash structure is required, and can be achieved via the new and improved concepts or technologies for the composite material for crash beam applications that lead to an increased utilisation of the composites and improved crash beam solutions (Startsev, Ponomareva and Anikhovskaya, 2013). Composites in the Production of Crash Structure The composite processing durations are lengthy, their raw materials, for example resins and fibres are relatively expensive, in addition, it not easy to achieve high quality object surface finishes. Hence, the material has been in existence for more than fifty years but their use in the high volume car manufacture is still limited or low. Most of the car parts, including the crash beam, are made from steel; the material, steel, is the favourite choice in the majority of vehicle assembly applications (Li, Chen, and Sun, 2010). Nowadays polymers, for example thermoplastics are commonly utilised in the automotive parts since they avail high production rates through injection moulding. Thermoplastic materials are regularly utilised in the manufacture of high dimensional precision components (ACI, 2011). The structural long fibre reinforced thermoplastic structures are being used in the automotive industry, for example the glass reinforced polypropylene, are replacing the existing casted aluminium frames. The material can be bolted easily and is 27% lighter when compared to the aluminium. In addition, its manufacturing or production cycle time is about 4 minutes less than that of aluminium. The structural thermoplastic components are also known to provide enhanced or elevated levels of energy absorption (Eom, 2009). The Aston Martin uses carbon fibre monocoque that is bonded to the extruded aluminium substructure, with rear and front glass reinforced polyester crash structure elements (Materials Today, 2008). As seen in figure 2, the carbon fibre performs exemplary well. Figure 2. The characteristics of lightweight materials (Materials Today, 2008) Figure 3. Car bod production path (Materials Today, 2008) Plastics are utilised extensively in rear and front ends of cars, since they have high specific energy absorption. The plastics avail extensive freedom in terms of shaping while maintaining shape, dimensional stability, with the high function integration. Besides the high energy absorption and high stiffness-to-weight ratio, the thermoplastic foams have high noise absorption characteristics. The Aston Martin front crash beam is predominantly made of carbon fibre. Technical Issues in the Composites Crash Structure Application Repair It is easy to take the component to the workshop for repair since they are light; the parts are easily disassembled. Design and the Structural Simulation The composites require specialists in the materials and process knowledge in terms of functional integration, orthotropic behaviour, light-weighting, and the styling freedom. One of the biggest or major problems associated with the composite design in the automotive industry is the availability of the simulation tools; composite materials are not easy to be characterised (Quadrini, 2007). Crashworthiness For the crash beam manufactured using composite material, it should be unable deform and instead should absorb energy meant for the passengers in to avert hard impacts on the occupants. The Aston Martin crash structure should embrace the first layer of glass fibres that are aligned in one direction; then the second layer with carbon fibres that are laid at 90 degrees towards the first layer in order to maintain or improve the integrity of the glass fibres in case of the crash(Quadrini, 2007). Manufacturing The crash beam composite structures are not widely utilised in the mass production of car because of the high costs of the raw materials; this also integrates with unsuitable manufacturing or production processes (Hossain, 2008). Tools utilised in the composite production or manufactures cheaper when compared to tools utilised in sheet metal forming; the composite production process is one-shot procedure, uses one mould, on other hand the sheet metal forming entails five to six separated tools in each component line. Savings on tool costs is influential at the low production rates, but the competitiveness is absent at the higher volumes that part costs are dominant (Quadrini, 2007). The widely available “composite” manufacturing or production processes for the high production volumes or quantities are the bulk moulding compound (BMC) and short fibre reinforced thermoplastic injection moulding processes. Merits of injection moulding include the short cycle times and do not produce scrap. The compression moulding utilising the glass mat thermoplastic (GMT) or the sheet moulding compound (SMC) are two options; they are highly automated and have reduced cycle times. The SMC has solved problems associated with high density of material, surface finish and the paintability requirements. However, GMT and SMC require post-machining and are usually associated with the production of scrap; when producing the crash beam using SMC, for example, there is need for milling holes in order to ensure light assembly; hence produces scrap (ACI, 2012). The third processing method in composite production is the resin transfer moulding (the RTM). This is the best method for structural applications, for example the crash beam, because of its easy automation, improved material tolerances and the better achievable mechanical properties (Wang, 2007). The RTM structure have good surface finish too. However, the RTM exhibit relatively high production tool costs with relatively high quantity of material waste. The cycle times for the RTM composites are also relatively long. Lightweighting Lightweighting of crash beam structure reduction translates into an increased performance of the care; the Aston Martin’s accelerations or top speed. Moreover, through lightweighting reduces fuel consumption and CO2 and other related emissions. Lightweighting is associated with additional cost; this is the main constraint in achieving lightweight designs. Material manufacturers are currently involved in the development or production of the new light and cost-effective materials, for example, the carbon fibre reinforced composites. The carbon fibre only weighs only 49% of aluminium equivalents or 30% of steel equivalents. In addition, the production cost of the material is reduced to approximately €10,000 when compared to approximately €40,000 for the similar car (Starr, 2010). Joining The joining process is critical aspect in the production or design and manufacturing of the crash beam. Every crash beam joints interrupt the structural geometry, hence creating the material discontinuities, with problems associated with local peak stresses. Joining problems countered by combining materials instead of them in isolation. The “hybrid” crash beam structure would exhibit improved properties; dissimilar materials are reliant on the joining technologies (Nixdorf, 2011). The crash structure joints can be achieved via the mechanical fastening, adhesive bonding, and welding or the fusion bonding. The crash beam hybrid methodology includes fastening with adhesive bonding (ACI, 2008). Figure 4. Front crash structure of the Aston Martin (Nixdorf, 2011) Recycling Metals are the ideal candidates for recycling since they lose their “memory” in terms of their previous life whenever melted down, as compared to composite. Modelling Modelling and the numerical simulation for the crash beam structure are essential in its production. The structure is undergoes the static, noise, dynamic, vibration, and handling analyses before manufacturing. The models are utilised since they increase the precision or accuracy (Tsoi and Zhuge, 2013). New Material Concepts The beam structure is manufactured with consideration of future replacement with better material (Hayaty and Esfandeh, 2010). The is achieved via modelling and simulation using the material properties. Why Use Carbon Fibre The carbon fibre composites are applied in the difficult service applications, for example, military jet fighters, hence proves to be effective in the crash structure (Stark, 2013). The material possesses infinite fatigue strength, provided that the strain values are maintained at reasonable level, which is at 0.3% (Cheng and Yuan, 2014). The epoxy resins utilised have the glass transition temperatures approaching, usually exceeding 150ºC in most cases, this makes them suitable for the front crash beam since there is presence of engine. In case of crash situations, the carbon fibre absorbs collision energy leaving the passenger safe (Cheng and Yuan, 2014). Most the carbon fibre components utilised in production vehicles do pass road durability, simulated hail testing, crash, and cold or hot slamming tests. Conclusion The composite materials have numerous potentials in beam manufacture; however the composite industry has to demonstrate their advantages crash beam application. Utilisation of the nine-layer carbon fibre in the crash structure offers an extremely rigid and lightweight crash structure (Evans, 2011). The carbon fibre tunnel has high strength-to-weight ratio as compared to its competitor; aluminium. In order for aluminium to avail the same levels of rigidity or strength, approximately twice heavy in weight aluminium is required. The carbon fibre utilisation will provide improved insulation from the exhaust and transmission (Wei, Zhang and Jiang, 2015). The main body structure for the Aston Martin should include a stiff carbon composite construction in rear and front crash structure with the superplastically formed aluminium on the composite outer panels. The will ensure an increased safety and lightweight for the car. References Adewuyi, O., and Okoli, O. (2012). The UV curing of composite components manufactured under the RIDFT process. Plastics, Rubber and Composites, 41(6), pp.247-255. Ali, S., and Sharma, A. (2014). Curing of the natural fibre-reinforced thermoplastic composites. Journal of Reinforced Plastics and Composites, 33(11), pp.995-999. Automotive Engineering: Lightweight, Functional, and Novel Materials. (2008). Materials Today, 11(7), p.44. Cheng, F., and Yuan, J. (2014). Glass fiber-coir hybrid composites. Fibers and Polymers, 15(9), pp.1714-1721. Eom, H. (2009). The High-Frequency Induction Heating. Polymer-Plastics Technology and Engineering, 48(12), pp.1072-1077. Evans, A. (2011). Lightweight Materials. 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